Splitter blades were designed for the impeller of a multi-blade centrifugal fan in a range hood. The effects of different radial positions, circumferential positions of short blades, and number of splitter blade pairs on the overall noise performance of the fan were studied in detail through experimental testing methods. The results showed that an optimized design of splitter blades could reduce the noise power of the range hood by 0.9 dB(A) under the same airflow volume. Flow field simulations and analyses indicated that the optimal design could reduce 10% area of the flow separation zone in the original blade passage, effectively suppressing the development of the separation vortices.